Wheels

F1 wheels are usually made from forged magnesium alloy due its low density and high strength. They are machined in one piece to make them as strong as possible, and are secured onto the suspension uprights by a single central locking wheel nut. This 'lock' is quickly pushed in to release the wheel during a pit stop, and the tyre changer then pulls it again to lock the wheel once the tyres have ben changed.

The teams buy wheels from companies such as OZ Racing, Enkei and Fondmetal. Once at the track, teams deliver their bare wheel rims to the tyre manufacturers truck where the tyres are put onto the rims with special machines. The tyres are then inflated and delivered back to the teams.

Wheel tethers

Since 1998, F1 cars have had to fit wheel tethers connecting the wheels to the chassis. This rule was introduced to try to stop wheels coming free and bouncing around dangerously during an accident. Unfortunately, wheels still do come off the cars during crashes, tragically killing a marshall at the Italian GP in 2000. The FIA have introduced an extra tether to each wheel for the 2001 season to try to stop the wheels coming off and causing injury to other drivers, marshals or spectators. The tether must attach to the chassis at one end, with the other end connecting to the wheel hub.

The wheel tethers are made by one of three companies in the UK, Future Fibres in London being one of them, and take the form of a rope. The tethers used in F1 are a derivative of high performance marine ropes, made especially for each car. They are made from a special polymer called polybenzoaoxide (PBO) which is often called Zylon. This Zylon material has a very high strength and stiffness characteristic (around 280GPa) much like carbon, but the advantage of Zylon is that it can be used as a pure fibre unlike carbon which has to be in composite form to gain its strength. The drawback of Zylon is that is must be protected from light, so it is covered in a shrink wrapped protective cover. The tethers are designed to withstand about 5000 kg of load, but often they can break quite easily during an accident, especially if the cable gets twisted by the broken suspension members. The teams normally replace the tethers every two or three races to ensure that they can withstand the loads put on them during an accident.